GHSA-r7w7-9xr2-qq2r langchain-openai: Image token counting SSRF protection can be bypassed via DNS rebinding

• PyPI langchain-openai: < 1.1.14 → fixed in 1.1.14

Summary `langchain-openai`'s `_url_to_size()` helper (used by `get_num_tokens_from_messages` for image token counting) validated URLs for SSRF protection and then fetched them in a separate network operation with independent DNS resolution. This left a TOCTOU / DNS rebinding window: an attacker-controlled hostname could resolve to a public IP during validation and then to a private/localhost IP during the actual fetch. The practical impact is limited because the fetched response body is passed directly to Pillow's `Image.open()` to extract dimensions — the response content is never returned, logged, or otherwise exposed to the caller. An attacker cannot exfiltrate data from internal services through this path. A potential risk is blind probing (inferring whether an internal host/port is open based on timing or error behavior). Affected versions • `langchain-openai` = 1.1.14 (requires `langchain-core` >= 1.2.31) Affected code File: `libs/partners/openai/langchain_openai/chat_models/base.py` — `_url_to_size()` The vulnerable pattern was a validate-then-fetch with separate DNS resolution: ```python validate_safe_url(image_source, allow_private=False, allow_http=True) ... separate network operation with independent DNS resolution ... response = httpx.get(image_source, timeout=timeout) ``` Fix The fix replaces the validate-then-fetch pattern with an SSRF-safe httpx transport (`SSRFSafeSyncTransport` from `langchain-core`) that: • Resolves DNS once and validates all returned IPs against a policy (private ranges, cloud metadata, localhost, k8s internal DNS) • Pins the connection to the validated IP, eliminating the DNS rebinding window • Disables redirect following to prevent redirect-based SSRF bypasses This fix was released in langchain-openai 1.1.14.